Effect of bleaching agents on inorganic components of human enamel

Objectives: To evaluate chemical alterations in the human enamel submitted to four bleaching techniques with industrialized and manipulated gels using extracted human molars Methods: Twenty extracted third molar, which were divided into four groups (n=5), where the buccal face received bleaching solution and the lingual face served as control group: G1=35% manipulated hydrogen peroxide (Artesanal Drugstore), activated with artificial saliva for 5 minutes followed by 3 consecutive and identical applications (4 sessions), G2=35% hydrogen peroxide (Whiteness HP-FGM), activated with a hybrid light (Whitening Lase–DMC) for 3 minutes, after which whitening gel was kept on the buccal surface for one (1) more minute, with 3 consecutive and identical applications (4 sessions), G3=16% manipulated carbamide peroxide (Artesanal Drugstore) activated with artificial saliva for 2 hours, twice a day during four (4) weeks, G4=16% carbamide peroxide (Whiteness Perfect-FGM), same methodology of group 3. After each session of bleaching, specimens were stored in artificial saliva at 37ºC. After the complete bleaching treatment for each group, specimens were stored in artificial saliva at 37ºC for 7 days, then teeth were sectioned in the mesio-distal axis and submitted to chemical analysis, which was performed using an Energy Dispersive Spectroscopy (LEO ZEISS 1450 VP) Results: A significant reduction in oxygen levels and an increase of phosphorus and calcium was verified for all buccal faces. There was no statistical significant difference on the findings among the results obtained in the 4 groups, which leads to the Conclusion: the manipulated whitening gels as well as the manufactured gels tested in this study caused alteration on the inorganic components of human enamel. Further studies are necessary to verify the consequences of these modifications.